LTC1174HVCS8#TR [Linear]
LTC1174 - High Efficiency Step-Down and Inverting DC/DC Converter; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C;
| 型号： | LTC1174HVCS8#TR |
| 厂家： | 
Linear |
| 描述： | LTC1174 - High Efficiency Step-Down and Inverting DC/DC Converter; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C |
| 文件： | 总20页 (文件大小：256K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1174
LTC1174-3.3/LTC1174-5
High Efficiency
Step-Down and Inverting
DC/DC Converter
U
FEATURES
DESCRIPTIO
The LTC®1174 is a simple current mode DC/DC converter
ideally suited for 9V to 5V, 5V to 3.3V or 5V to –5V
operation. With an internal 0.9Ω switch (at a supply
voltage of 9V), the LTC1174 requires only four external
components to construct a complete high efficiency
DC/DC converter.
■
High Efficiency: Up to 94%
■
Peak Inductor Current Independent of
Inductor Value
Short-Circuit Protection
■
■
Optimized for 5V to –5V Applications
■
Wide VIN Range: 4V to 18.5V
■
Low Dropout Operation
UnderanoloadconditiontheLTC1174drawsonly130µA.
In shutdown, it draws a mere 1µA making this converter
ideal for current sensitive applications. In dropout, the
internal P-channel MOSFET switch is turned on continu-
ously allowing the user to maximize the life of the battery
source.
■
Low-Battery Detector
■
Pin Selectable Current Limit
■
Internal 0.9Ω Power Switch: VIN = 9V
■
Only Four External Components Required
■
130µA Standby Current
■
Active Low Micropower Shutdown
The maximum inductor current of the LTC1174 family is
pin selectable to either 340mA or 600mA, optimizing
efficiency for a wide range of applications. Operation up to
200kHz permits the use of small surface mount inductors
and capacitors.
U
APPLICATIO S
■
Distributed Power Systems
■
Step-Down Converters
■
Inverting Converters
For applications requiring higher output current or ultra-
high efficiency, see the LTC1148 data sheet.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
■
Memory Backup Supply
■
Portable Instruments
■
Battery-Powered Equipment
U
TYPICAL APPLICATIO
High Efficiency Step-Down Converter
LTC1174-5 Efficiency
100
V
IN
9V
95
15µF*
25V
+
6
V
= 6V
IN
V
IN
×3
3
2
8
1
5
90
85
80
75
70
LB
LB
SHUTDOWN
IN
V
= 9V
IN
V
OUT
OUT
SW
5V
175mA
7
I
PGM
100µH†
LTC1174-5
+
100µF**
10V
1N5818
GND
4
L = 100µH
V
= 5V
= 0V
OUT
PGM
1174 TA01
I
(3) AVX TPSD156K025
AVX TPSD107K010
*
**
1
10
LOAD CURRENT (mA)
100 200
† COILTRONICS CTX100-4
1174 TA02
1174fe
1
LTC1174
LTC1174-3.3/LTC1174-5
W W U W
ABSOLUTE AXI U RATI GS
(Note 1)
(Voltage Referred to GND Pin)
Input Supply Voltage (Pin 6)
LTC1174........................................... –0.3V to 13.5V
LTC1174HV ...................................... –0.3V to 18.5V
Switch Current (Pin 5) .............................................. 1A
Switch Voltage (Pin 5)
Operating Temperature Range
LTC1174CX ............................................ 0°C to 70°C
LTC1174IX ........................................ –40°C to 85°C
Junction Temperature (Note 2)............................ 125°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
LTC1174................................................. VIN – 13.5V
LTC1174HV ............................................ VIN – 18.5V
U W
U
PACKAGE/ORDER I FOR ATIO
TOP VIEW
TOP VIEW
V (V *)
OUT FB
1
2
3
4
8
7
6
5
SHUTDOWN
V
(V *)
OUT FB
1
2
3
4
SHUTDOWN
8
7
6
5
LB
I
LB
I
OUT
PGM
OUT
PGM
LB
IN
V
IN
LB
IN
GND
V
IN
GND
SW
SW
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE
8-LEAD PDIP
* ADJUSTABLE OUTPUT VERSION
* ADJUSTABLE OUTPUT VERSION
TJMAX = 125°C, θJA = 150°C/W
TJMAX = 125°C, θJA = 110°C/W
ORDER PART NUMBER
ORDER PART NUMBER
S8 PART MARKING
LTC1174CN8
LTC1174CS8
1174
LTC1174CN8-3.3
LTC1174CN8-5
LTC1174IN8
LTC1174CS8-3.3
LTC1174CS8-5
LTC1174IS8
117433
117450
1174I
LTC1174HVCN8
LTC1174HVCN8-3.3
LTC1174HVCN8-5
LTC1174HVCS8
LTC1174HVCS8-3.3
LTC1174HVCS8-5
LTC1174HVIS8
1174H
1174H3
1174H5
1174HI
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The
●
denotes specifications which apply over the full operating
= V , I = 0V, unless otherwise noted.
temperature range, otherwise specifications are at T = 25°C. V = 9V, V
A
IN
SHUTDOWN
IN PGM
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
1
UNITS
µA
I
Feedback Current
LTC1174/LTC1174HV
LTC1174/LTC1174HV
FB
V
V
Feedback Voltage
●
1.20
1.25
1.30
V
FB
Regulated Output Voltage
LTC1174-3.3/LTC1174HV-3.3
LTC1174-5/LTC1174V-5
●
●
3.14
4.75
3.30
5.00
3.46
5.25
V
V
OUT
∆V
OUT
Output Voltage Line Regulation
V
= 6V to 12V, I
= 100mA, I
= V (Note 3)
10
70
mV
IN
LOAD
PGM
IN
1174fe
2
LTC1174
LTC1174-3.3/LTC1174-5
ELECTRICAL CHARACTERISTICS
The
●
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T = 25°C. V = 9V, V
= V , I
= 0V, unless otherwise noted.
A
IN
SHUTDOWN
IN PGM
SYMBOL PARAMETER
Output Voltage Load Regulation
CONDITIONS
MIN
TYP
MAX
UNITS
LTC1174-3.3 (Note 3)
20mA < I
20mA < I
< 175mA, I
< 400mA, I
= 0V
–5
–45
–70
–70
mV
mV
LOAD
LOAD
PGM
PGM
= V
IN
LTC1174-5 (Note 3)
20mA < I
20mA < I
< 175mA, I
< 400mA, I
= 0V
–5
–50
–70
–70
mV
mV
LOAD
LOAD
PGM
PGM
= V
IN
I
Input DC Supply Current (Note 4)
Active Mode
Q
LTC1174: 4V < V < 12V, I
= 0V
PGM
450
450
600
600
µA
µA
IN
PGM
LTC1174HV: 4V < V < 16V, I
= 0V
IN
Sleep Mode
LTC1174: 4V < V < 12V
130
130
180
180
µA
µA
IN
LTC1174HV: 4V < V < 16V
IN
SHUTDOWN (Note 4)
LTC1174: V
= 0V, 4V < V < 12V
1
2
10
25
µA
µA
SHUTDOWN
IN
LTC1174HV: V
= 0V, 4V < V < 16V
IN
SHUTDOWN
V
Low-Battery Trip Point
Current into Pin 3
1.25
1.4
0.5
V
LBTRIP
I
I
µA
mA
mA
LBIN
Current Sunk by Pin 2
LTC1174: V
= 0.4V
LBOUT
LBOUT
1.0
0.6
1.2
0.8
1.5
1.5
LBOUT
LTC1174HV: V
= 0.4V
V
Comparator Hysteresis
Current Limit
LTC1174/LTC1174HV
7.5
15
30
mV
HYST
I
I
I
= V , V
= 0V
= 0V
●
●
0.54
0.27
0.60
0.34
0.83
0.53
A
A
PEAK
PGM
PGM
IN OUT
= 0V, V
OUT
R
ON
ON Resistance of Switch
LTC1174
LTC1174HV
●
●
0.75
0.90
1.30
1.55
Ω
Ω
t
Switch Off-Time (Note 6)
SHUTDOWN Pin High
V
at Regulated Value
3
4
5
µs
V
OFF
OUT
V
V
Minimum Voltage at Pin 8 for Device to Be Active
Maximum Voltage at Pin 8 for Device to Be in Shutdown
LTC1174: V = 12V
1.2
IH
IL
SHUTDOWN Pin Low
0.75
V
I
SHUTDOWN Pin Input Current
0.5
2.0
µA
µA
IH
SHUTDOWN
SHUTDOWN
LTC1174HV: V
= 16V
I
SHUTDOWN Pin Input Current
0 ≤ V
≤ 0.8V
SHUTDOWN
0.5
µA
IL
The
●
denotes specifications which apply over the full operating temperature range,
otherwise specifications are at –40°C ≤ T ≤ 85°C. LTC1174I and LTC1174HVI Only.
A
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Feedback Voltage
LTC1174I/LTC1174HVI
●
1.18
1.25
1.31
V
FB
I
Current Sunk by Pin 2
V
V
= 0.4V (LTC1174I)
= 0.4V (LTC1174HVI)
●
●
0.75
0.50
1.2
0.8
2.0
1.6
mA
mA
LBOUT
LBOUT
LBOUT
I
Current Limit
I
I
= V , V
= 0V (LTC1174I)
= 0V (LTC1174I)
●
0.54
0.60
0.34
0.84
A
A
PEAK
PGM
PGM
IN OUT
OUT
= 0V, V
I
I
= V , V
= 0V (LTC1174HVI)
= 0V (LTC1174HVI)
●
0.5
0.60
0.34
0.86
A
A
PGM
PGM
IN OUT
= 0V, V
OUT
t
Switch Off-Time (Note 6)
Switch On Resistance
V
V
at Regulated Value (LTC1174I)
at Regulated Value (LTC1174HVI)
●
●
2.0
1.8
4
4
6.0
6.2
µs
µs
Ω
OFF
OUT
OUT
R
LTC1174I/LTC1174HVI
●
0.9
1.7
ON
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: T is calculated from the ambient temperature T and power
J A
dissipation P according to the following formulas:
D
LTC1174CN8, LTC1174CN8-3.3, LTC1174CN8-5:
T = T + (P × 110°C/W)
J
A
D
LTC1174CS8, LTC1174CS8-3.3, LTC1174CS8-5:
T = T + (P × 150°C/W)
J
A
D
1174fe
3
LTC1174
LTC1174-3.3/LTC1174-5
ELECTRICAL CHARACTERISTICS
Note 3: Guaranteed by design.
Note 5: Current into Pin 6 only, measured without electrolytic input
capacitor.
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 6: The off-time is wafer-sort trimmed.
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency vs Load Current
Efficiency vs Load Current
Efficiency vs Load Current
100
95
90
85
80
75
70
100
95
90
85
80
75
70
100
95
90
85
80
75
70
V
= 6V
IN
V
= 6V
IN
V
= 6V
IN
V
= 9V
IN
V
= 9V
IN
V
= 9V
IN
L = 50µH
L = 50µH
L = 100µH
V
PGM
COIL = CTX50-4
= 5V
= 0V
OUT
V
PGM
COIL = CTX50-4
= 5V
V
= 5V
OUT
OUT
I
I
= V
I
= V
IN
PGM IN
COIL = CTX100-4
1
10
LOAD CURRENT (mA)
100 200
1
10
100
400
1
10
100
500
LOAD CURRENT (mA)
LOAD CURRENT (mA)
1174 G01
1174 G02
1174 G03
Efficiency vs Load Current
Efficiency vs Load Current
Efficiency vs Load Current
100
90
80
70
60
50
100
90
80
70
60
50
100
90
80
70
60
50
V
= 5V
IN
V
= 5V
V
V
IN
= 5V
IN
V
= 9V
= 9V
V
= 9V
IN
IN
IN
L = 50µH
V
L = 50µH
L = 100µH
= 3.3V
V
= 3.3V
V
= 3.3V
OUT
PGM
OUT
PGM
COIL = CTX50-4
OUT
I
= 0V
I
= V
I
= V
IN
PGM IN
COIL = CTX100-4
COIL = CTX50-4
1
10
100
300
1
10
100
500
1
10
100 500
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
1174 G04
1174 G05
1174 G06
1174fe
4
LTC1174
LTC1174-3.3/LTC1174-5
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Switch Leakage Current
vs Temperature
Line Regulation
Efficiency vs Input Voltage
6
4
180
160
140
120
100
80
95
V
= 13.5V
I
I
= 100mA
= 0V
IN
LOAD
PGM
94
93
2
0
L = 100µH
92
–2
–4
–6
–8
–10
–12
–14
L = 50µH
91
90
60
V
I
I
= 5V
89
88
87
OUT
PGM
LOAD
40
= 0V
= 75mA
20
CORE = CTX (Kool Mµ®)
0
0
4
6
8
10
12
14
0
20
40
60
100
2
80
9
5
7
10 11 12 13 14
6
8
INPUT VOLTAGE (V)
TEMPERATURE (°C)
INPUT VOLTAGE (V)
1174 G07
1174 G08
1174 G09
DC Supply Current
Supply Current in Shutdown
Efficiency vs Input Voltage
500
450
400
350
300
250
200
150
100
50
95
94
93
92
91
90
89
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
I
= 0V
PGM
ACTIVE MODE
V
= 5V
OUT
L = 100µH
COIL = CTX100-4
SHUTDOWN = 0V
T
= 25°C
A
I
= V
IN
PGM
CURRENT INTO PIN 6 ONLY
I = 100mA
LOAD
I = 0V
PGM
I
= 300mA
LOAD
I
= V
PGM
IN
SLEEP MODE
T
= 25°C
A
0
0
4
6
8
10
12
14
2
5
6
7
8
9
10 11 12 13 14
0
4
6
8
10
12
14
2
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1174 G12
1174 G10
1174 G11
Operating Frequency
vs V – V
Switch Resistance vs
Input Voltage
Off-Time vs Output Voltage
IN
OUT
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
50
40
30
20
10
0
2.0
1.5
1.0
0.5
0
T = 25°C
A
V
= 5V
OUT
T
= 25°C
A
T
A
= 70°C
LTC1174HV
LTC1174
LTC1174-5
LTC1174HV-5
LTC1174-3.3
LTC1174HV-3.3
5
7
0
2
3
6
8
9
4
6
10 12
14 16 18 20
INPUT VOLTAGE (V)
0
1
3
4
5
1
4
8
2
(V – V ) VOLTAGE (V)
OUTPUT VOLTAGE (V)
IN
OUT
1174 G13
1174 G14
1174 G15
1174fe
5
LTC1174
LTC1174-3.3/LTC1174-5
U
U
U
PI FU CTIO S
SW(Pin5):DrainoftheP-ChannelMOSFETSwitch.Cathode
V
OUT (VFB)(Pin1):FortheLTC1174,thispinconnectstothe
of Schottky diode must be closely connected to this pin.
main voltage comparator’s input. On the LTC1174-3.3 and
LTC1174-5 this pin goes to an internal resistive divider
which sets the output voltage.
VIN (Pin 6): Input Supply Voltage. It must be decoupled
close to ground Pin 4.
LBOUT (Pin 2): Open Drain of an N-Channel Pull-Down. This
pin will sink current when Pin 3 (LBIN) goes below 1.25V.
During shutdown the state of this pin is indeterminate.
IPGM (Pin 7): Selects the Current Limit of the P-Channel
Switch. With IPGM = VIN, the current trip point is 600mA and
with IPGM = 0V, the current trip value is reduced to 340mA.
LBIN (Pin 3): The “–” Input of the Low-Battery Voltage
Comparator. The “+” input is connected to a reference
voltage of 1.25V.
SHUTDOWN (Pin 8): Pulling this pin to ground keeps the
internal switch off and puts the LTC1174 in micropower
shutdown.
GND (Pin 4): Ground Pin.
U
U
W
FU CTIO AL DIAGRA
(Pin 1 connection shown for LTC1174-3.3 and LTC1174-5, changes create LTC1174)
V
IN
6
V
V
LIM2
LIM1
+
I
PGM
7
R
SENSE
0.1Ω
A5
SLEEP
V
TH2
+
–
–
A2
–
+
A4
RESET
SET
Q
C
g
V
FB
T
m
V
(V )
OUT FB
V
TH1
1
5
×
SW
LB
IN
3
R1*
LB
OUT
2
4
V
FB
–
+
–
+
A1
31.5k
A3
SHUTDOWN
1.25V
REFERENCE
8
GND
1174 BD
* R1 = 51k FOR LTC1174-3.3
R1 = 93.5k FOR LTC1174-5
1174fe
6
LTC1174
LTC1174-3.3/LTC1174-5
U
OPERATIO
(Refer to Functional Diagram)
The LTC1174 uses a constant off-time architecture to
switch its internal P-channel power MOSFET. The off-time
is set by an internal timing capacitor and the operating
frequency is a function of VIN.
In sleep mode, the LTC1174 is in standby and the load
current is supplied by the output capacitor. All unused
circuitry is shut off, reducing quiescent current from
0.45mAto0.13mA.Whentheoutputcapacitordischarges
by the amount of the hysteresis of the comparator A1, the
P-channel switch turns on again and the process repeats
itself.
The output voltage is set by an internal resistive divider
(LTC1174-3.3 and LTC1174-5) or an external divider re-
turned to VFB Pin 1 (LTC1174). A voltage comparator A1
compares the divided output voltage to a reference voltage
of 1.25V.
Operating Frequency and Inductor
Since the LTC1174 utilizes a constant off-time architecture,
itsoperatingfrequencyisdependentonthevalueofVIN.The
frequency of operation can be expressed as:
Tooptimizeefficiency, theLTC1174automaticallyswitches
between continuous and Burst Mode® operation. The volt-
age comparator is the primary control element when the
device is in Burst Mode operation, while the current com-
parator controls the output voltage in continuous mode.
V − V
V + VD
IN
⎛
⎞
1
tOFF
IN
OUT
f =
Hz
( )
⎜
⎝
⎟
⎠
During the switch“ON” time, switch current flows through
the 0.1Ω sense resistor. When this current reaches the
thresholdofthecurrentcomparatorA2,itsoutputsignalwill
change state, setting the flip-flop and turning the switch off.
The timing capacitor, CT, begins to discharge until its
voltage goes below VTH1. Comparator A4 will then trip,
which resets the flip-flop and causes the switch to turn on
again. Also, the timing capacitor is recharged. The inductor
current will again ramp up until the current comparator A2
trips. The cycle then repeats.
wheretOFF =4µsandVDisthevoltagedropacrossthediode.
Note that the operating frequency is a function of the input
and ouput voltage.
Although the size of the inductor does not affect the fre-
quency, it does affect the ripple current. The peak-to-peak
ripple current is given by:
V
OUT
+ VD
L
⎛
⎜
⎝
⎞
⎟
⎠
IRIPPLE = 4 •10−6
A
P−P
(
)
When the load is relatively light, the LTC1174 automatically
goes into Burst Mode operation. The current mode loop is
interrupted when the output voltage reaches the desired
regulated value. The hysteretic voltage comparator A1 trips
when VOUT is above the desired output voltage, shutting off
the switch and causing the timing capacitor to discharge.
This capacitor discharges past VTH1 until its voltage drops
below VTH2. Comparator A5 then trips and a sleep signal is
generated.
By choosing a smaller inductor, a low ESR output filter
capacitorhastobeused(seeCIN andCOUT).Moreover,core
losswillalsoincrease(seeInductorCoreSelectionsection)
due to higher ripple current.
Burst Mode is a registered trademark of Linear Technology Corporation.
1174fe
7
LTC1174
LTC1174-3.3/LTC1174-5
W U U
U
APPLICATIO S I FOR ATIO
Inductor Core Selection
a premium larger gauge wire can be used to reduce the wire
resistance. This also prevents excessive heat dissipation.
With the value of L selected, the type of inductor must be
chosen. Basically there are two kinds of losses in an
inductor, core and copper
CIN
In continuous mode the source current of the P-channel
MOSFETisasquarewaveofdutycycleVOUT/VIN.Toprevent
large voltage transients, a low ESR input capacitor sized for
the maximum RMS current must be used. The CIN RMS
current is given by:
Core losses are dependent on the peak-to-peak ripple
current and the core material. However it is independent of
the physical size of the core. By increasing the inductance
the inductor’s peak-to-peak ripple current will decrease,
therefore reducing core loss. Utilizing low core loss mate-
rial, such as molypermalloy or Kool Mµ will allow users to
concentrate on reducing copper loss and preventing satu-
ration.Figure1showstheeffectofdifferentcorematerialon
the efficiency of the LTC1174. The CTX core is Kool Mµ and
the CTXP core is powdered iron (material 52).
1/2
]
IOUT
V
V − V
(
)
[
OUT IN OUT
IRMS
≈
A
RMS
(
)
V
IN
This formula has a maximum at VIN = 2VOUT, where IRMS
=
IOUT/2.Thissimpleworstcaseiscommonlyusedfordesign
becauseevensignificantdeviationsdonotoffermuchrelief.
Note that ripple current directly affects capacitor’s lifetime.
DONOTUNDERSPECIFYTHISCOMPONENT.Anadditional
0.1µF ceramic capacitor is also required on VIN for high
frequency decoupling.
Although higher inductance reduces core loss, it increases
copperlossasitrequiresmorewindings.Whenspaceisnot
100
CTX100-4
90
COUT
CTX100-4P
80
To avoid overheating, the output capacitor must be sized to
handle the ripple current generated by the inductor. The
worst case RMS ripple current in the output capacitor is
given by:
70
V
V
PGM
= 5V
60
50
IN
= 3.3V
IN
OUT
I
= V
IPEAK
IRMS
≈
A
RMS
(
)
1
10
100
500
2
LOAD CURRENT (mA)
= 170mA or 300mA
100
90
80
70
60
50
Although the output voltage ripple is determined by the
hysteresis of the voltage comparator, ESR of the output
capacitor is also a concern. Too high of an ESR will create
ahigherrippleoutputvoltageandatthesametimecausethe
LTC1174 to sleep less often. This will affect the efficiency of
the LTC1174. For a given technology, ESR is a direct
function of the volume of the capacitor. Several small-sized
capacitors can also be paralleled to obtain the same ESR as
one large can. Manufacturers such as Nichicon, Chemicon
and Sprague should be considered for high performance
capacitors. The OS-CON semiconductor dielectric capaci-
tor available from Sanyo has the lowest ESR for its size, at
CTX50-4
CTX50-4P
V
= 5V
IN
V
= 3.3V
IN
OUT
I
= V
PGM
1
10
100
500
LOAD CURRENT (mA)
1174 F01
Figure 1. Efficiency Using Different Types of
Inductor Core Material
a higher price.
1174fe
8
LTC1174
LTC1174-3.3/LTC1174-5
U
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APPLICATIO S I FOR ATIO
Catch Diode Selection
comparedwitha1.25Vreferencevoltage. Withthecurrent
going into Pin 3 being negligible, the following expression
is used for setting the trip limit:
Thecatchdiodecarriesloadcurrentduringtheoff-time.The
average diode current is therefore dependent on the
P-channel switch duty cycle. At high input voltages the
diode conducts most of the time. As VIN approaches VOUT
the diode conducts only a small fraction of the time. The
most stressful condition for the diode is when the output is
short-circuited. Under this condition the diode must safely
handleIPEAKatcloseto100%dutycycle.Afastswitchingdiode
must also be used to optimize efficiency. Schottky diodes are
a good choice for low forward drop and fast switching times.
Most LTC1174 circuits will be well served by either a 1N5818,
a MBRS140T3 or a MBR0520L Schottky diode.
⎛
⎝
R4⎞
VLBTRIP = 1.25 1+
⎜
⎟
⎠
R3
When the LTC1174 is shut down, the low-battery detector
is inactive.
V
IN
LTC1174
R4
R3
3
–
+
1.25V
REFERENCE
Short-Circuit Protection
1174 F03
The LTC1174 is protected from output short by its internal
current limit. Depending on the condition of IPGM pin, the
limit is either set to 340mA or 600mA. In addition, the off-
time of the switch is increased to allow the inductor’s
current to decay far enough to prevent any current build-up
(see Figure 2).
Figure 3. Low-Battery Comparator
LTC1174 Adjustable/Low Noise Applications
The LTC1174 develops a 1.25V reference voltage between
thefeedback(Pin1)terminalandground(seeFigure4).By
selecting resistor R1, a constant current is caused to flow
through R1 and R2 to set the overall output voltage. The
regulated output voltage is determined by:
IPGM = VIN
2
R1
⎛
⎝
R ⎞
VOUT = 1.25 1+
⎜
⎟
⎠
IPGM = 0
For most applications, a 30k resistor is suggested for R1.
To prevent stray pickup, a 100pF capacitor is suggested
across R1 located close to the LTC1174. Alternatively, a
capacitor across R2 can be used to increase the switching
frequency for low noise operation.
GND
1174 F02
L = 100µH
VIN = 13.5V
20µs/DIV
Figure 2. Inductor's Current with Output Shorted
Inverting Applications
Low-Battery Detector
The LTC1174 can easily be set up for a negative output
voltage. If –5V is desired, the LTC1174-5 is ideal for this
application as it requires the least components. Figure 5
shows the schematic for this application. Note that the
Thelow-batteryindicatorsensestheinputvoltagethrough
anexternalresistivedivider. Thisdividedvoltageconnects
to the “–” input of a voltage comparator (Pin 3) which is
1174fe
9
LTC1174
LTC1174-3.3/LTC1174-5
W U U
U
APPLICATIO S I FOR ATIO
V
OUT
LTC1174-5 regulator and also to one or more loads in
parallel with the the regulator’s VIN. If the battery is dis-
connected while the LTC1174/LTC1174-3.3/LTC1174-5
regulator is supplying a light load and one of the parallel
circuitsisaheavyload,theinputcapacitoroftheLTC1174/
LTC1174-3.3/LTC1174-5regulatorcouldbepulleddown
faster than the output capacitor, causing the absolute
maximum ratings to be exceeded. The result is often a
latchup which can be destructive if VIN is reapplied. Bat-
terydisconnectispossibleasaresultofmechanicalstress,
bad battery contacts or use of a lithium-ion battery with
a built-in internal disconnect. The user needs to assess
his/her application to determine whether this situation
could occur. If so, additional protection is necessary.
6.8nF**
R2
R1
1
LTC1174
V
FB
100pF*
ADJUSTABLE APPLICATIONS
LOW NOISE APPLICATIONS
*
1174 F04
**
Figure 4. LTC1174 Adjustable Configuration
INPUT VOLTAGE
4V TO 12V
47µF*
+
6
16V
0.1µF
V
IN
×2
3
2
7
8
1
5
LB
LB
SHUTDOWN
IN
Prevention against latchup can be accomplished by sim-
ply connecting a Schottky diode across the SW and VIN
pins as shown in Figure 6. The diode will normally be
reverse biased unless VIN is pulled below VOUT at which
time the diode will clamp the (VOUT – VIN) potential to less
than the 0.6V required for latchup. Note that a low leakage
Schottky should be used to minimize the effect on no-load
supplycurrent.SchottkydiodessuchasMBR0530,BAS85
and BAT84 work well. Another more serious effect of the
protection diode leakage is that at no load with nothing to
provide a sink for this leakage current, the output voltage
can potentially float above the maximum allowable toler-
ance. To prevent this from occuring, a resistor must be
connected between VOUT and ground with a value low
enough to sink the maximum possible leakage current.
V
OUT
OUT
SW
I
PGM
50µH**
LTC1174HV-5
GND
+
47µF*
16V
×2
MBRS140T3
4
V
OUT
–5V
45mA
1174 F05
AVX TPSD476K016
COILTRONICS CTX50-4
*
**
Figure 5. Positive-to-Negative 5V Converter
output voltage is now taken off the GND pin. Therefore,
the maximum input voltage is now determined by the
differencebetweentheabsolutemaximumvoltagerating
and the output voltage. A maximum of 12V is specified in
Figure5,givingthecircuita1.5VofheadroomforVIN.Note
that the circuit can operate from a minimum of 4V, making
it ideal for a 4 NiCad cell application. For a higher output
current circuit, please refer to the Typical Applications
section.
LATCHUP
PROTECTION
SCHOTTKY
Absolute Maximum Ratings and Latchup Prevention
V
V
SW
LTC1174
OUT
IN
TheabsolutemaximumratingsspecifythatSW(Pin5)can
neverexceedVIN (Pin6)bymorethan0.3V.Normallythis
situation should never occur. It could, however, if the
output is held up while the supply is pulled down. A con-
ditionwherethiscouldpotentiallyoccuriswhenabattery
is supplying power to an LTC1174/LTC1174-3.3/
+
LTC1174-3.3
LTC1174-5
1174 F06
Figure 6. Preventing Absolute Maximum
Ratings from Being Exceeded
1174fe
10
LTC1174
LTC1174-3.3/LTC1174-5
U
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APPLICATIO S I FOR ATIO
Board Layout Checklist
DESIGN EXAMPLE
As a design example, assume VIN = 9V (nominal), VOUT
5V, and IOUT = 350mA maximum. The LTC1174-5 is used
forthisapplication,withIPGM (Pin7)connectedtoVIN.The
minmum value of L is determined by assuming the
LTC1174-5 is operating in continuous mode.
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC1174. These items are also illustrated graphically in
the layout diagram in Figure 7. Check the following in your
layout:
=
1. Is the Schottky catch diode closely connected between
ground (Pin 4) and switch (Pin 5)?
I
PEAK
= I
OUT
AVG CURRENT
2. Is the “+” plate of CIN closely connected to VIN (Pin 6)?
This capacitor provides the AC current to the internal
P-channel MOSFET.
I
+ I
V
PEAK
2
=
I
V
= 350mA
3. Is the 0.1µF VIN decoupling capacitor closely conected
between VIN (Pin 6) and ground (Pin 4)? This capacitor
carries the high frequency peak currents.
TIME
1174 F08
Figure 8. Continuous Inductor Current
4. Is the SHUTDOWN (Pin 8) actively pulled to VIN during
normal operation? The SHUTDOWN pin is high imped-
ance and must not be allowed to float.
With IOUT = 350mA and IPEAK = 0.6A (IPGM = VIN), IV =
0.1A.The peak-to-peak ripple inductor current, IRIPPLE, is
0.5A and is also equal to:
5. Is the IPGM (Pin 7) pulled either to VIN or ground? The
IPGM pin is high impedance and must not be allowed
to float.
V
+ VD
⎛
⎜
⎝
⎞
⎟
⎠
OUT
IRIPPLE = 4 •10−6
A
P−P
(
)
L
8
1
2
3
V
OUT
FB
SHUTDOWN
(V
)
7
6
LB
LB
I
OUT
OUTPUT DIVIDER
REQUIRED WITH
ADJUSTABLE
PGM
R1
R2
V
V
V
IN
IN
IN
LTC1174
+
0.1µF
VERSION ONLY
C
IN
4
5
SW
GND
D
L
BOLD LINES INDICATE
HIGH CURRENT PATH
C
OUT
+
OUT
1174 F07
Figure 7. LTC1174 Layout Diagram (See Board Layout Checklist)
1174fe
11
LTC1174
LTC1174-3.3/LTC1174-5
W U U
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APPLICATIO S I FOR ATIO
Solving for L in the above equation and with VD = 0.6V,
L = 44.8µH. The next higher standard value of L is 50µH
(example:CoiltronicsCTX50-4). Theoperatingfrequency,
neglecting voltage across diode VD is:
NowallowVIN todropto6V.Atthisminimuminputvoltage
the operating frequency will decrease. The new frequency
is 42kHz.
Table 1. Inductor Manufacturers
MANUFACTURER
PART NUMBER
VOUT
VIN
⎛
⎝
⎞
f ≈ 2.5 •105 1−
Coilcraft
DT3316 Series
⎜
⎟
⎠
1102 Silver Lake Road
Cary, IL 60013
(708) 639-2361
= 111kHz
Coiltronics Inc.
Econo-Pac
Octa-Pac
With the value of L determined, the requirements for CIN
and COUT are calculated. For CIN, its RMS current rating
should be at least:
6000 Park of Commerce Blvd.
Boca Raton, FL 33487
(407) 241-7876
Gowanda Electronics Corporation
1 Industrial Place
Gowanda, NY 14070
GA10 Series
1/2
IOUT
V
V − V
(
)
]
[
OUT IN OUT
IRMS
=
A
RMS
(
)
(716) 532-2234
V
IN
Sumida Electric Co. Ltd.
637 E. Golf Road, Suite 209
Arlington Heights, IL 60005
(708) 956-0666/7
CD 54 Series
CD 75 Series
= 174mA
For COUT, the RMS current rating should be at least:
IPEAK
Table 2. Capacitor Manufacturers
MANUFACTURER
AVX Corporation
P.O. Box 887
IRMS
≈
A
RMS
(
)
PART NUMBER
2
TPS Series
TAJ Series
= 300mA
Myrtle Beach, SC 29578
(803) 448-9411
Nichicon America Corporation
927 East State Parkway
Schaberg, IL 60173
PL Series
(708) 843-7500
Sanyo Video Components
2001 Sanyo Avenue
San Diego, CA 92173
(619) 661-6385
OS-CON Series
Attn: Sales Dept.
1174fe
12
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
6V to 5V Step-Down Regulator with Low-Battery Detection
INPUT VOLTAGE
6V
+
+
47µF**
16V
6
0.1µF
4.7k
LOW-BATTERY INDICATOR
*
V
IN
×2
IS SET TO TRIP AT V = 5.5V
IN
*LOW-
BATTERY
8
1
5
7
2
3
I
SHUTDOWN
PGM
AVX TPSD476K016
= MBRS140T3 (SURFACE MOUNT)
1N5818
**
D1
INDICATOR
LB
V
OUT
OUT
162k
† L1 SELECTION
LTC1174-5
V
OUT
MANUFACTURER PART NO. TYPE
SW
5V
LB
IN
L1†
100µH
COILTRONICS
SUMIDA
GOWANDA
CTX100-4 SURFACE MOUNT
CD75-101 SURFACE MOUNT
GA10-103K THROUGH HOLE
365mA
47µF**
16V
×2
GND
4
47.5k
D1
1174 TA03
High Efficiency 3.3V Regulator
INPUT VOLTAGE
4V TO 12.5V
+
22µF*
6
25V
0.1µF
V
IN
×3
8
1
7
3
I
SHUTDOWN
PGM
LB
LB
V
IN
OUT
50µH†
LTC1174-3.3
V
OUT
2
5
SW
3.3V
OUT
425mA
47µF**
16V
×2
+
GND
4
AVX TPSD226K025
*
1N5818
AVX TPSD476K016
**
† COILTRONICS CTX50-4
1174 TA04
1174fe
13
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
Low Noise 3V Regulator
INPUT VOLTAGE
4V TO 12.5V
+
22µF*
6
25V
0.1µF
V
IN
×3
8
1
5
7
I
SHUTDOWN
PGM
3
LB
IN
V
FB
50µH†
V
6.8nF
LTC1174
OUT
2
LB
OUT
3V
SW
450mA
42k
30k
GND
4
100µF**
10V
×2
+
1N5818
AVX TPSD226K025
AVX TPSD105K010
*
**
1174 TA05
† COILTRONICS CTX50-4
Positive-to-Negative (–5V) Converter
INPUT VOLTAGE
4V TO 12.5V
*LOW-BATTERY INDICATOR
V
(V) I
4
6
8
10
(mA)
IN
OUT MAX
110
IS SET TO TRIP AT V = 4.4V
IN
+
+
10µF**
35V
6
**AVX TPSD106K035
***AVX TPSD105K010
D1= MBRS130LT3 (SURFACE MOUNT)
1N5818
0.1µF
4.7K
140
V
IN
×2
170
*LOW-
BATTERY
8
7
2
3
I
SHUTDOWN
PGM
200
† L1 SELECTION
12.5
235
INDICATOR
1
5
LB
LB
V
OUT
OUT
SW
280k
LTC1174HV-5
MANUFACTURER
PART NO.
CTX50-3
DT3316-473
CD54-470
GA10-472K
TYPE
IN
COILTRONICS
COILCRAFT
SUMIDA
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
L1†
50µH
GND
4
100µF***
10V
43k
D1
GOWANDA
V
OUT
–5V
1174 TA06
1174fe
14
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
Positive-to-Negative (– 3.3V) Converter
INPUT VOLTAGE
4V TO 13.5V
* LOW-BATTERY INDICATOR
+
+
33µF**
20V
IS SET TO TRIP AT V = 4.4V
6
IN
V
(V) I
4
5
6
7
(mA)
IN
OUT MAX
175
0.1µF
4.7K
** AVX TPSD336K020
*** AVX TPSD105K010
D1 = MBRS140T3 (SURFACE MOUNT)
1N5818
V
IN
×2
*LOW-
BATTERY
8
1
5
7
2
3
205
I
SHUTDOWN
PGM
230
255
INDICATOR
† L1 SELECTION
LB
LB
V
OUT
OUT
220k
LTC1174HV-3.3
SW
MANUFACTURER
PART NO.
TYPE
IN
COILTRONICS
COILCRAFT
SUMIDA
CTX50-3
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
L1†
50µH
100µF***
10V
×2
DT3316-473
CD54-470
GA10-472K
GND
4
43k
D1
V
OUT
GOWANDA
–3.3V
1174 TA07
210mA
Negative Boost Converter
AVX TPSD336K020
*
D1
6
= MBRS140T3 (SURFACE MOUNT)
1N5818
V
IN
310k
50k
† L1 SELECTION
8
7
2
3
I
SHUTDOWN
PGM
MANUFACTURER
PART NO.
TYPE
+
33µF*
20V
1
5
0.1µF
COILTRONICS
COILCRAFT
SUMIDA
CTX50-3
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
LB
OUT
V
OUT
DT3316-473
CD54-470
GA10-472K
×2
LTC1174-3.3
SW
LB
IN
GOWANDA
+
33µF*
16V
×2
0.1µF
L1†
50µH
GND
4
D1
V
OUT
–9V
1174 TA08
175mA
INPUT VOLTAGE
–5V
1174fe
15
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
9V to 5V Pre-Post Regulator
INPUT
VOLTAGE
6V TO 12.5V
+
6
100µF*
16V
0.1µF
V
IN
3
2
7
8
1
5
SANYO OS-CON
*
**
D1
LB
LB
SHUTDOWN
IN
AVX TPSD476K016
= MBRS140T3 (SURFACE MOUNT)
1N5818
V
OUT
FB
†
V
LTC1174
L1 SELECTION
OUT
8
5
1
V
OUT
LT®1121-5
5V
I
SW
IN
PGM
L1†
MANUFACTURER PART NO.
TYPE
SURFACE MOUNT
DT3316-473 SURFACE MOUNT
CD54-470 SURFACE MOUNT
GA10-472K THROUGH HOLE
150mA
110k††
30.1k††
GND
4
COILTRONICS
COILCRAFT
SUMIDA
CTX50-3
50µH
+
+
1µF
SOLID
TANTALUM
SHUTDOWN
47µF**
16V, ×2
100pF
0.1µF
D1
GND
3
GOWANDA
†† USE 1% METAL FILM RESISTORS
1174 TA09
LCD Display Power Supply
INPUT
V
IN
(V)
I
4
(mA)
OUT MAX
20
VOLTAGE
4V TO 12.5V
5
6
25
56.2k††
6
30
7
35
V
IN
8
43
3
8
1
5
LB
SHUTDOWN
IN
2N2222
2N5210
9
50
10
11
12
55
7
2
50k††
60
I
PGM
V
FB
65
LTC1174
LB
SW
OUT
AVX TAJE106K050
AVX TPSD476K016
= MBRS140T3 (SURFACE MOUNT)
1N5818
*
1N914
GND
4
998k††
**
Si9435
D1
D1
0.1µF
V
OUT
† L1 SELECTION
–24V
+
47µF**
16V
×2
50mA AT
MANUFACTURER PART NO.
TYPE
SURFACE MOUNT
DT3316-104 SURFACE MOUNT
CD75-101 SURFACE MOUNT
GA10-103K THROUGH HOLE
0.1µF
V
IN
= 9V
10µF*
50V
L1†
100µH
COILTRONICS
COILCRAFT
SUMIDA
CTX100-3
+
×4
GOWANDA
1174 TA10
††
USE 1% METAL FILM RESISTORS
1174fe
16
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
9V to 5V, –5V Outputs
INPUT VOLTAGE
4V TO 12.5V
SANYO OS-CON
WIMA MKS2
*
+
**
6
100µF*
† COILTRONICS CTX100-4
0.1µF
0.1µF
20V
V
IN
V
(V)
I
(mA)
8
1
5
7
IN
OUT MAX
75
I
SHUTDOWN
PGM
4
6
100
3
2
LB
LB
V
8
IN
LTC1174HV-5
OUT
OUT
125
V
OUT
3.3µF**
10
12
13
145
5V
135mA AT
= 9V
160
SW
L1A†
100µH
180
V
IN
GND
4
L1B†
100µH
+
100µF*
16V
3
2
MBRS140T3
MBRS140T3
CTX100-4
L1A
L1B
1
4
+
100µF*
16V
–V
OUT
–5V
1174 TA11
135mA AT
V
IN
= 9V
9V to 12V, –12V Outputs
INPUT VOLTAGE
4V TO 12.5V
* AVX TAJD226K035
** WIMA MKS2
+
22µF*
6
3
2
† COILTRONICS CTX100-4
0.1µF
35V
V
†† USE 1% METAL FILM RESISTORS
IN
SHUTDOWN
CTX100-4
L1A
×3
L1B
8
7
I
1
4
PGM
V
IN
(V)
I
4
(mA)
OUT MAX
20
1
5
3
2
LB
LB
V
IN
FB
3.3µF**
5
6
25
V
OUT
LTC1174
Si9430DY
35
12V
SW
OUT
L1A†
2
100µH
7
45
55mA AT
IN
1
50
301k††
34k††
4
3
8
V
= 9V
GND
4
+
22µF*
35V
×2
L1B†
100µH
9
55
1N914
10
11
12
62
MBRS140T3
67
73
+
22µF*
35V
×2
–V
MBRS140T3
OUT
–12V
1174 TA12
55mA AT
V
IN
= 9V
1174fe
17
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO S
Automatic Current Selection
INPUT
VOLTAGE
6V TO 12.5V
6
100k
V
IN
8
1
5
2
LB
I
SHUTDOWN
TPO610L
OUT
+
100µF*
7
3
V
0.1µF
PGM
OUT
20V
V
50µH†
OUT
LTC1174-5
5V
LB
SW
IN
0mA TO
320mA
GND
4
100k
100k
+
100µF*
16V
1N5818
36.5k
SANYO OS-CON CAPACITOR
*
1174 TA13
† COILTRONICS CTX50-4
Buck-Boost Converter
INPUT VOLTAGE
4V TO 12V
+
6
100µF*
20V
0.1µF
V
IN
8
1
5
7
I
SHUTDOWN
PGM
* SANYO OS-CON
** WIMA MKS2
3
2
† COILTRONICS CTX100-4
IN
OUT
SW
LB
LB
V
3.3µF**
V
LTC1174HV-5
OUT
5V
160mA
OUT
L1A†
100µH
2
1
4
3
GND
4
3
2
L2A†
100µH
+
CTX100-4
L1A
100µF*
16V
L1B
1N5818
1
4
1174 TA14
1174fe
18
LTC1174
LTC1174-3.3/LTC1174-5
U
PACKAGE DESCRIPTIO
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.400*
(10.160)
MAX
.130 ± .005
(3.302 ± 0.127)
.300 – .325
(7.620 – 8.255)
.045 – .065
(1.143 – 1.651)
8
1
7
6
5
.065
(1.651)
TYP
.255 ± .015*
(6.477 ± 0.381)
.008 – .015
(0.203 – 0.381)
.120
.020
(0.508)
MIN
(3.048)
MIN
+.035
–.015
2
4
3
.325
.018 ± .003
(0.457 ± 0.076)
.100
(2.54)
BSC
N8 1002
+0.889
8.255
(
)
–0.381
NOTE:
INCHES
1. DIMENSIONS ARE
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
.045 ±.005
NOTE 3
.050 BSC
7
5
8
6
.245
MIN
.160 ±.005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
1
3
4
2
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
× 45°
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
NOTE:
INCHES
1. DIMENSIONS IN
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
SO8 0303
1174fe
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
19
LTC1174
LTC1174-3.3/LTC1174-5
U
TYPICAL APPLICATIO
Battery Charger
INPUT VOLTAGE
8V TO 12.5V
V
(V)
I
8
9
10
11
12
(mA)
IN
OUT MAX
320
+
22µF*
20V
* AVX TAJD226K020
** AVX TAJD107K010
D1,D2 = MBRS140T3
(SURFACE MOUNT)
1N5818
6
0.1µF
325
V
IN
×2
8
1
5
330
7
I
SHUTDOWN
PGM
335
335
† L1 SELECTION
3
2
LB
LB
V
FB
IN
D2
MANUFACTURER
PART NO.
TYPE
LTC1174
V
OUT
TO
SW
COILTRONICS
COILCRAFT
SUMIDA
CTX50-2P
DT3316-473
CD54-470
GA10-472K
SURFACE MOUNT
SURFACE MOUNT
SURFACE MOUNT
THROUGH HOLE
OUT
4 NiCAD BATTERY
L1†
50µH
150k
GND
4
+
100µF**
10V
GOWANDA
D1
33k
1174 TA15
RELATED PARTS
PART NUMBER
LT®1074/LT1076
LTC1147
DESCRIPTION
Step-Down Switching Regulator
High Efficiency Step-Down DC/DC Controller
COMMENTS
100kHz, 5A (LT1074) or 2A (LT1076) Monolithic
8-Pin Controller
LTC1265
1.2A High Efficiency Step-Down DC/DC Regulator
1.5A 500kHz Step-Down Switching Regulator
High Efficiency Step-Down DC/DC Regulator
Inverting 1.4MHz Switching Regulator in SOT-23
1MHz Step-Down DC/DC Converter in SOT-23
High Efficiency Synchronous Step-Down Regulator
Burst Mode Operation, Monolithic
High Frequency Small Inductor
LTC1174 with Internal Schottky Diode
LT1375/LT1376
LTC1574
LT1611
–5V at 150mA from 5V Input, 1mV Output Ripple, SOT-23 Package
P-P
LTC1701
V
V
= 2.5V to 5.5V, I = 135µA, V
= 5V to 1.25V
OUT
IN
Q
LTC1707
= 2.85 to 8.5V, Selectable Burst Mode Operation,
IN
600mA Output Current, SO-8 Package
LTC1877
High Efficiency Synchronous Step-Down Regulator
600mA at V = 5V, 2.65V to 10V = V , I = 10µA
IN
IN Q
1174fe
LT 1006 REV E • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
20
●
●
© LINEAR TECHNOLOGY CORPORATION 1994
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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